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Hardtopper
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13,043 Posts
Discussion Starter · #1 ·
My car was getting street tuned today before it gets tuned on the dyno on june 4th... we got the car pretty much good up until about 5K RPMS to be on the safe side, a very conservative tune...the car is actually driveable now. We are having one issue though, first off my car is a 96 with an OBD1 conversion.... I did have a CEL before I went NA-T but I did not know what it was for... I got the CEL today and I checked it and it was 52, which means Knock Sensor (front). Well here is what happens... I can drive my car on no boost at all and the car is fine, no CEL no nothing... as soon as there is ANY sign of boost the car throws the Code 52 CEL.. and I mean ANY kind of boost. We figured we should take the tap from the SAFC2 to the knock sensor off, so we did.... and still got the same problem. When the Code 52 CEL goes off the computer tries to correct and overide the VPC/SAFC settings which makes it sluggish but manageable at a safe A/F. We backed down the base timing to 5 degrees to be on the safe side and the car still does it...

We came to the conclusion that the front knock sensor is bad and may need to be replaced. I cannot get the car tuned completely until we fix that Code 52 CEL. If anyone could let me know what the possibilities may be please let me know, any and all help is greatly appreciated.


Regards,
Kirk :freak: :lol:
 

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Hardtopper
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13,043 Posts
Discussion Starter · #2 ·
The more and more I do research, thinking, and looking at the TSRM the more I think I didnt even plug it in or something stupid like that......... :lol:
 

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Hardtopper
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13,043 Posts
Discussion Starter · #3 ·
Its plugged in.... bad sensor maybe????
 

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565rwhp Turbo Lexus
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727 Posts
Maybe not much help here, but code 52 is also knock sensor on an MR2 Turbo.

When that codes pops up ... we always reset the ECU. When we would start the car, no CEL would be there, BUT as soon as you get it going over like 5 MPH, then the CEL pops back on.... that means 100% bad sensor. If you reset the ECU and it goes away and then you drive and it doesn't come back on, the sensor is OK, it was just telling you that it did detect knock ..... and it retarded the timing to ensure safety to your motor.

In the MR2 Turbo, the sensor is very sensitive and it is pretty easy to *blow* the sensor and need a replacement. There is a GM knock sensor replacement that seems to be less touchy and I always upgraded to that ....

Again, this is how it works with MR2 Turbos ... I assume that it is probably the same ... you might want to look into replacing the sensor.
 

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Hardtopper
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13,043 Posts
Discussion Starter · #5 ·
Back when I owned a MK3 supra... the Code 52 was also popular and they would actually rewire their knock sensors which was a PAIN.

I reset the ECU many times yesterday.. its not necessarily when the car gets on boost, sometimes when I kick the idle up with the gas pedal in order not to stall on 1st gear (I <3 VPC :lol:) it will do it aswell.... I can be driving normal and it pops up out of nowhere and the car runs like ass. We tuned it as much as we could to about 4500RPMS only under boost, but the ECU tries to fight it real bad...car would stumble a bit before getting on boost then moves.... we kept the A/F mid to low 11's to be on the safe side for now and atleast have a driveable car
 

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565rwhp Turbo Lexus
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727 Posts
Sounds to me like you need to replace the sensor. Symptoms are the same as the MR2 Turbo.

Don't take my word for it tho, wait for some other replies :)
 

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Hardtopper
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13,043 Posts
Discussion Starter · #7 ·
Thanks for your help man

Also if anyone knows, when the knock sensor detects any kind of knock it would not throw a CEL correct? Code 52 strictly means its not getting signal back from the sensor or something is wrong with it? I am going to try to source another knock sensor and replace it... thankfully its coming from the front and not rear.. so I wont have to drop the starter
 

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Hardtopper
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13,043 Posts
Discussion Starter · #8 ·
I found the problem... car ran PERFECT with the code out on boost.. the wire for it came undone from the knock sensor and I plugged it back in.. I just didnt have time to look for it at the time I got the code since it was late at night. The car just threw 3 codes on the way back home and runs like pure crap unless @ WOT.... stumbles alot on lower end driving normal for some reason... I got mainly O2 sensor codes and the car runs real lean under normal driving... I'll look at it after work tomorrow... probably melted some wires or something, who knows.. :lol:

Ran perfect all night long until I came home... mid to low 11 A/F's to be on the safe side, base timing of 5 degrees @ 10psi on 10:1 and the car feels strong. Can't wait to lower compression and let it rip....cant imagine how fast thats got to be :bigthumb:
 
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